The primary objective of this study was to histologically validate the assumption that Endoscopic Sleeve Gastroplasty (ESG) induces full-thickness scarring and long-term fibrosis similar to surgical Sleeve Gastrectomy (SG). While Laparoscopic Sleeve Gastrectomy (LSG) creates a high-pressure system via irreversible anatomical restriction, recent physiological data suggest ESG functions as a compliance-sparing "low-pressure" system that preserves esophageal motility. Consequently, we hypothesized that the restrictive mechanism of ESG relies on delayed emptying rather than the structural rigidity seen in surgery. This study analyzed gastric wall fibrosis and muscular thickness in patients undergoing SG after previous ESG versus primary SG to determine if ESG induces the tissue remodeling necessary for permanent distensibility reduction.

This study was designed as a blinded, comparative histopathological evaluation of gastric specimens. The study population consisted of patients undergoing rescue SG after a prior ESG (ESG-SG group) and a control group undergoing primary SG (SG group). All specimens were evaluated by a pathologist blinded to group allocation to ensure objective assessment. Key histological metrics included submucosal fibrosis thickness (mm), muscularis propria thickness (mm), and fibrosis extension (classified as submucosa only vs. submucosa + muscle). Statistical analysis included the Shapiro–Wilk test for normality, with group comparisons performed using Mann–Whitney tests, Welch t-tests, and Fisher’s exact test.

A total of twenty-two patients were included in the analysis (11 in the ESG-SG group and 11 in the SG group). The histopathological analysis revealed no significant structural differences between the two groups. Submucosal fibrosis thickness was comparable, with a negligible mean difference of +0.11 mm (95% CI –1.04 to +1.26 mm). Similarly, muscularis propria thickness did not differ significantly between groups (p = 0.84), and fibrosis extension patterns were identical (p = 1.00), showing no qualitative differences in depth or architecture.

Parameter    ESG-SG Group (n=11)    SG Group (n=11)    P-value

Submucosal Fibrosis (Mean ± SD)    3.29 ± 1.21 mm    3.18 ± 1.37 mm    0.895*

Submucosal Fibrosis (Median)    2.9 mm    3.3 mm    -

Muscularis Propria Thickness (Mean ± SD)    1.58 ± 0.63 mm    1.45 ± 0.48 mm    0.84

Fibrosis Extension (Pattern/Depth)    Identical distribution    Identical distribution    1.00†

*Mann–Whitney U test; †Fisher’s exact test

This blinded histopathological analysis demonstrates that gastric wall architecture after ESG does not exhibit increased submucosal fibrosis, greater muscular thickness, or deeper fibrosis extension compared to primary SG. These findings challenge the widespread assumption that ESG mimics the full-thickness scarring of surgical resection. Instead, the absence of structural stiffening supports the classification of ESG as a "low-pressure" system where clinical efficacy is likely driven by motility modulation (decelerated gastric emptying) rather than the irreversible reduction of distensibility characteristic of high-pressure surgical sleeves. This distinction positions ESG as a mechanistic entity separate from resection-based surgery, aligning with recent evidence of preserved esophageal physiology.